When trying to save structures, even when Include Entities is ON, entities aren't saving.
Either it is saving and is unable to load (also with Include Entities ON), or it doesn't save in the first place.
This was tested with armor stands, area effect clouds, pigs, etc...
boq
Confirmed. The structure loader still removes
UUIDLeastandUUIDMostinstead ofUUID, causing the UUID of the old mob to be used and the mob skipped. This is probably the cause of MC-175239 as well.